According to recent statistics of the International Energy Agency (IEA), it is known that at least 10% of average domestic power consumption of OECD nations is wasted as standby electric power. Standby electric power refers to electric power which is continuously consumed for any reason even when electronic devices are not used while power plugs of the electronic device are generally connected to receptacles. In recent years, effective cutoff of standby electric power is becoming one of the most important problems in increasing energy efficiency of various electronic devices.
Currently, the number of charging devices used worldwide is enormous, and it is known that when it comes only to mobile phones, about 4.8 billion charging devices are used. When the number of charging devices for various electric tools is added, the total number of charging device cannot be imagined. In more detail, for example, when it is assumed that a time period for which a user does not actually use a charging device in a day is 20 hours and the charging device is continuously inserted into a receptacle, standby power of about 0.5 W may be wasted on average for each charging device, in which case electric power of about 2.4 GWH is wasted in a day before the user knows. Accordingly, corresponding standby power is wasted, and economic loss is nationally caused to produce electric power unnecessarily wasted in this way and carbon dioxide is consistently generated due to use of fossil fuels, which may ultimately cause various problems such as environmental contamination.
According to the related art, if a power source device is separated from a receptacle even though a smartphone is fully charged or separated, standby power is generated in the power source device, wasting unnecessary power.
Korean Patent No. 10-1024381 of the applicant relates to a power supply device including a standby power cutoff structure, and discloses a power supply device which can completely cut off standby power even when a plug is not withdrawn if a battery of an electronic product is fully charged or a power source of an electronic product is switched off. However, because the patent has a structure in which a switch is connected to supply electric power when a connector is connected to connect an electronic product to a power source device so that it is inevitably necessary to add a mechanical switch, the size of a connection unit becomes large. In addition, because a switch element is added, manufacturing costs of the product increase. In addition, in the patent, although a power source device should be connected to an electronic product (for example, a laptop computer or a tablet PC) and a power switch of the electronic product should be switched on to operate an adapter (power source device), the user feel rather inconvenienced because the power source device starts to supply electric power.
Korean Patent No. 10-1178193 (Korean Patent Application Publication No. 10-2010-0082063) of the applicant discloses a receptacle device having a function of automatically cutting of standby power and a method of controlling the same. In the patent, because it cannot be recognized when a signal will be input again even if electric power of a product is cut off and a sleep mode is started, a wake-up mode should be performed again within at least one second. Accordingly, although power directly consumed in a receptacle of the power source device can be reduced, wasted electric power cannot be still ignored.